Closed fluid-operated free-pump system with three concentric tubings



March 18, 1952 c OBERLY 2,589,669

CLOSED FLUID- OPERATED FREE-PUMP SYSTEM WITH THREE CONCENTRIC TUBINGS 1 Filed May 16, 1949 2 Sl-lEETS-Sl-IEET l /N VENTOR.

CLARENCE d. COBERLY 5? Hi5 ATTORNEYS.

HARRIS, K/ECH, F OSTERG: HF) ems March 18, 1952 c. J. COBERLY 2,589,669

CLOSED FLUID-OPERATED FREE-PUMP SYSTEM WITH THREE CONCENTRIC TUBINGS Filed May 16, 1949 2 SHEETSSHEET 2 rid/ 9 .9 44 -402 1 58 H 7 -a do 1: 96 -2; 1g; 97 1 7 44 //v VENTOR.

CLARENCE. d. COBERLY BY HIS HTTORNE Y5.

HARE/61K CH, Fosns/e & HARE/5 Patented Mar. 18, 1952 CLOSED FLUID-OPERATED FREE-PUMP SY TEM WITH THREE CONCENTRIC TUBINGS Clarence J. Coberly, Los Angeles, Calif., assignor, by mesne assignments, to Dresser Equipment Company, Cleve land, Ohio, a corporation of Ohio Application May is, 19149, Serial No. 93,481

21 Claims.

My invention relates in general to tubing systerms for fluid-operatedwell pumps and, more particularly, to a closed tubing system for a fluidoperated well pump of the co-call-ed free type. Reference is hereby made to my copending applications Serial No. 93,483, filed May 16, 1949, Serial No. 93,482, filed May 16, 1949, and Serial No. 93,484, filed May 16, 1949.

It is conventional in the oil industry to employ a well pump apparatus which includes a free fluid-operated pump, such a pump being movable into and out of the well through a tubing set in the-well and being adapted to assume an operating position at the lower end of such tubing. Examples of such fluid-operated, freepump systems are disclosed in my Patents Nos. 2,230,830, granted February 4, 1941, and 2,338,993, granted January 11, 1944. I

In conventional fluid-operated, free-pump systems, such as those disclosed in my aforementioned patents, two tubings are employed, one for conveying operating fluid downwardly in the well to the pump and the other for conveying fluid produced by the well upwardly therein from the pump to the surface, the two tubings being referred to hereinafter as the supply and production tubing's, respectively. In such conventional systems, the pump is movable into its operating position through the supply tubing. The supply and production tubings are interconnected at their lower ends in fluid communicatlion with each other and with the well so that the pump may receive operating fluid from the supply tubing and well fluid from the well and so that it may discharge well fluid into the production tubing as production fluid.

In installing such a free pump in the well, it is moved downwardly through the supply tubing into its operating position at the lower end thereof either by the action of gravity or by the application of fluid pressure to the upper end of the pump. After the pump has been installed in its operating position, operating fluid, which is usually clean crude oil, is delivered to the motor section of the pump under relatively high pressure through the supply tubing. As is well known in the art, such operating fluid is alternately directed by a suitable valve mechanism in the motor section of the pump to opposite ends of a'motor piston which is coupled to a pump piston in the pump section of the device, fluid from the well being admitted to the pump section by a suitable valve mechanism therein. Such alternating application of operating fluid pressure to the ends of the motor piston produces reciprocation of the motor and pump pistons with the result that the pump piston pumps fluid produced by the well into the production tubing, the latter conveying the production fluid upwardly therein to the surface. When removal of the pump from the well is desired for any reason, as for service or repair, fluid pressure is applied to the lower end of the pump to move it upwardly out of its operating position and through the supply tubing to the surface. This is accomplished conventionally by reversing the flow through the system so that operating fluid flows downwardly in the production tubing to the lower end of the pumpand acts on the pump to move it upwardly through the supply tubing to the surface.

In a conventional free-pump system of the foregoing character, the spend operating fluid discharged by the motor section of the pump is delivered to the production tubing so that the spent operating fluid and the production fluid are intermixed and conveyed upwardly together through the production tubing. Since the operating fluid delivered to the pump through the supply tubing must be clean, in order to prevent abrasion and corrosion of the moving parts of the pump, fresh operating fluid must be supplied to the system continuously. The c0ntinuous provision of such fresh operating fluid requires considerable surface equipment, normally in the form of settling tanks or fllters, which is expensive to install and operate. Also, in the particular arrangement hereinbefore mentioned wherein the pump is disposed in the supply tubing, the flow reversal necessary to remove thepump from the well may carry any sand or other foreign matter present in the production fluid into the supply tubing with the result that suchv foreign matter may enter the motor section of the pump upon resumption of operation after reinstallation with the attendant possibility of damage to the pump.

In view of the foregoing, it is a primary object of this invention to provide a closed systerm for the fluid-operated free pump which includes athird tubing separate from the supply and production tubings for returning the spent operating fluid to the surface independently of the well fluid, the tubing for returning the spent operating fluid being referred to hereinafter as the return tubing. With such a closed system, the spent. operating fluid is separately conveyed back to the surface for storage and re-use to actuate the fluid-operated pump so that there is very little loss of operating fluid from the sys tem and, consequently, the surface equipment necessary to supply'fresh operating fluid to the -system needs have only a relatively small capacity and can be relatively cheap and economical, both as regards initial cost and operating normally preventing direct flow between the tubings and the well by way of the pump receiver when the pump is in its operating position so costs. Also, the reversed flow necessary to move 1 the pump upwardly to the surface during removal of the pump may take place through the 3 return tubing to avoid carrying sand and other foreign matter into that portion of the system reserved for the operating fluid, which is an important feature. As will be pointed out in more detail hereinafter, further objects of the invention reside in certain modifications of the pump and in the tubing arrangements employed to provide such a closed system.

, Considering the invention more specifically, an object thereof is to provide a closed system for a fluid-operated, free pump comprising supply,

return and production tubings which are set in" the well and one of which is adapted to receive the pump and to provide an operating position for the pump at its lower end, the supply, return and production tubings respectively being adapted to convey operating fluid for actuating the pump downwardly into the well to the pump. spent operating fluid discharged by the pump upwardly in the well from the pump to the surface and production fluid discharged by the pump upwardly in the well from the pump to the surface.

An important object of the invention is to provide a closed system wherein the supply, return and production tubings are set in the well concentrically with the innermost tubing adapted to receive the pump.

Another object is to provide such a closed system wherein the three tubings are interconnected at their lower ends in fluid communica tion with each other and with the well so that the pump may, when in its operating position, receive operating fluid for its actuation from the supply tubing through an intake, discharge spent operating fluid into the return tubing through an exhaust, receive well fluid from the well through an inlet and discharge well fluid into the production tubing through an outlet.

Another object is to provide a closed system having means whereby a downward flow of fluid through one of the tubings, other than the tubing in which the pump is disposed, may be applied to the lower end of the pump to move it upwardly out of its operating position and through the tubing in which it is disposed to the surface V whenever removal of the pump from the well is seated on such seat when it is in its operating position.

Another object is to provide a pump receiver having passages which place the interior thereof in fluid communication with the supply, return and production tubings and with the well in such a manner as to provide fluid communication between the intake, the exhaust, the inlet and the outlet of the pump and the supply tubing, the return tubing, the well and the production tubing,

respectively, when the pump is disposed in the pump receiver and seated on the pump seat.

Another object is to provide sealing means for that operating fluid may flow only from the supply tubing through the motor section of the pump to the return tubing and so that well fluid may flow only from the well through the pump section of the pump to the production tubing. More specifically, an object in this connection is to provide a sealing means which, when the pump is in its operating position, places the supply tubing in fluid communication with only the intake of the pump, the return tubing in fluid communication with only the exhaust of the pump, the well in fluid communication with only the inlet of the pump and the production tubing in fluid communication with only the outlet of the pump.

Another object is to provide a system wherein the aforementioned sealing means comprises annular sealingelements which are carried by the;

pump receiver, and at its other end with a chamber in the pump receiver between the pump seat and the pump for applying a downward flow of fluid through such tubing to the lower end of the pump to move it upwardly out of the pump receiver and to the surface.

Another object is to provide a sealing device for normally preventing fluid flow between two of the tubings by way of the aforementioned passage means and the pump receiver when the pump is in its operating position. Another object in this connection is to provide a system wherein the aforementioned sealing device is an annular sealing element adapted to be disposed between .the pump and the pump receiver.

Another object is to provide a system wherein the tubing with which the aforementioned passage means communicates is thereturn tubing so that the pump may be moved upwardly to the surface by a downward flow of clean fluid through the return tubing to prevent introducing sand and other abrasive matter into the pump receiver. Still another object is to provide a closed system wherein the pump is movable into its operating position in the pump receiver through the supply tubing and wherein the pump is movable upwardly to the surface by a downward flow of clean fluid through the return tubing so as to avoid carrying any of the sand or other abrasive material which may be in the fluid in the production tubing into the pump receiver during the pump-removal operation.

Another object isto minimize the power required to overcome friction between the production fluid moving upwardly through the production-tubing and the wall of the production tubing by employing a production tubing having a large internal diameter. This feature is particularly important under well conditions such that a pump having a motor section of small capacity and a pump section of large capacity may be employed.

Another object of the invention is to provide a. closed system wherein the outermost of the concentric supply, return and production tubings is the casing of the well.

The foregoing objects andadvantagesof the.

which are described in detail hereinafter. Refer-- ring to the drawings:

'Fig. 1 is a utility viewof a closed, fluid-op.er ated, free-pump system which embodies the in.- vention;

Fig. 2 is an enlarged, horizontal sectional view taken along the broken line Z -Z of Fig. 1;

Fig. 3 is an enlarged, vertical sectional view taken along the broken line 3-3 of Fig. 2;

Fig. 4'is a downward continuation of Fig. 3;

Fig. 5 is a utility view of another embodiment of the invention;

Fig. 6 is an enlarged, horizontal sectional view taken along the broken line 66 of Fig. 5;

Fig. 7 is an enlarged, vertical sectional view taken along the broken line 1-1 of Fig. 6; and,

Fig. 8 is a downward continuation of Fig. '7.

Considering first the embodiment illustrated in Figs. 1 to 4 of the drawings with particular reference to Fig. 1 thereof, I show a well casing l5 which is set in an oil Well with its lower end open to an oil producing zone of the well as is well known in the art, the casing being provided with a casing head I6 at its upper end. Set in the well within the casing I5 is a closed tubing system which comprises concentric supply, return and production. tubings respectively designated by the numerals l8 and I9, the supply tubing being set within the return tubing and the return tubing' being set within the production tubing. The

tubings Hi and I9 are interconnected at their lower 'ends in fluid communication with each other and with the well by a tubular pump receiver .20 which is aligned with and which, in eifect, forms a downward extension of the innermost or supply tubing IT. The pump receiver 26 provides an operating position for a fluid-operated, free pump 2| which is movable downwardly through the sup-ply tubing l'l' into its operating position in the pump receiver, the internal diameter of the pump receiver being substantially equal to that of the supply tubing; As will be discussed in more detail hereinafter, the supply tubing H is adapted to convey operating fluid, such as clean crude oil, under pressure downwardly in the well from the surface to the pump 2| to actuate the pump, and the return tubing I8 is adapted to receive spent operating fluid discharged by the pump and to convey the spent operating fluid upwardly in the well to the surface. The pump 2| is adapted to receivewell fluid from the well and todischarge it into the production tubing I9 as production fluid, the production tubing conveying the production fluid upwardly in the well to the surface.

a The supply,.return and production tubings i8 and I9 are connected at their upper ends to a tubing head 21 which includes supply, return and production sections 28, 29 and 30 in fluid com-.. munication with the supply, return and'production tubings, respectively. Connected to the tub ing head sections 28, 29 and 39 in fluid communication therewith are supply, return and production lines 3|, 32 and 33 which respectivel communicate with the supply, return and production tubings l1, l8 and Hi through the corresponding tubing head sections. The supply line 3! leads to a suitable source (not shown) 'of operating fluidunder pressure, which source may be a conventional triplex pump having its intake connected to a suitable reservoir. The return line 32 leads to the reservoir and the production line 33 leads: to a suitable point of disposal or storage for the, production fluid. The tubing head 21 also in-.

cludes a tube 34 which is aligned with the supply tubing I1 and through which the pump 2| may. be inserted into or removed from the supply tub-- The tube 34 may have associated therewith mg. a pump catcher (not shown) for the pump 2|, the latter having at its upper end a tapered head 35 which is receivable by the pump catcher during removal of the pump from the well. The pump catcher may be of any suitable type, such as that "disclosed in my aforementioned Patent Referring now to Figs. 3 and 4 of the drawings and considering the'structure of the pump receiver 20, it includes an inner sleeve 39 whichis aligned with and which, in effect, form an extension of the supply tubing l1, an annular ele-: ment 46 being clamped between the supply tubing and the sleeve 39 by a coupling 4| threaded onto the lower end of the return tubing I3 and onto the upper end of the sleeve 39. ,It will be noted that the upper surface of the annular element 4t and the lower end of the supply tubing"- H are complementary tapered so that the annular element 40 serves to-center the lower end of the supply tubing in the return tubing. A spacer 40a having passages therethrough is disposedbetween the tubings I! and [8 above the element 411. Telescoped over the coupling 4| and sealed with respect thereto by 'an annular sealing element 42 is an outer sleeve 43which is spaced radially from the lower end of the coupling 4|- and from the inner sleeve 39 to provide an annular space 44 for spent operating fluid, the lower end of the coupling 4| being provided withports 45 therethrough so that spent operating fluid from the annular space 44 may flow throughsuch ports into the return tubing i8, 1. e., into the annular space between the supply tubing IT and the return. tubing. The spent operating fluid may enter the annular space 44 through radialports 46 in the inner sleeve 39 and through registering ports 41 in a liner 48 pressed into them--- ner sleeve 39.

Threaded into the lower end of theinner sleeve- 39 is another inner sleeve 5| which is threaded at its lower end into a bore 52 in a fitting 53-at' the lower end of the pump receiver 20, the outer sleeve 43 being telescoped over the upper end' of this fitting and being sealed with respect thereto by an annular sealing element 54. '.With' this construction, assembly of" the inner sleeves 39' and 5| and the outer sleeve 43 with the coupling The fitting 53 is provided at its lower end with" a tapered foot 5'! which is adapted to seat on a complementary seat 58 in a fitting 59 at the lower end of the production tubing l9. With this'con-- struction, the supply and return tubings l! and I8 and the pump receiver 20 may be'removed from'the well without removing the production tubing |9, which is a feature of the invention.

The bore 52 in the fitting 53 communicates with the well through a passage 60 in this fitting and through longitudinal and lateral passages 6| and 62 in the fitting 59 at the lower end of the.

production tubing. The bore-'52 in the fitting 53 tween the outer sleeve 43 and the production tubing I9, which annular space in turn communicates at its upper end with the annular space between the return tubing' l8 and the production tubing. Thus, with this construction, the pump receiver 20 interconnects the lower ends of the supply, return and production tubings l1, l8 and I9 in fluid communication with each other and with the well. 1 V

The fitting 53 of the pump receiver 20 is provided with a passage means 65 for applying a downward flow of fluid through the return tubing l8 to the lower end of the pump 2| to move the pump upwardly out of the pump receiver 20 and through the supply tubing I! to the surface when removal of the pump is desired for any reason, this passage means comprising one or more.

longitudinal passages 61 which communicate at their upper ends with the annular space 44 between the inner sleeves 39 and and the outer sleeve 43 and which communicate at their lower ends with an annular chamber 68 at the lower end of the pump 2|.

Disposed in the lower end of the bore 52 in the fitting 53 is an inlet fitting 12 for the pump 2|, the latter having an inlet which is adapted to receive well fluidfrom the well through the inlet fitting by way of the passages 60, 6| and 62 when the pump is in its operating position, as will be discussed in more detail hereinafter. As is well known in the art, the inlet fitting I2 is preferably provided with a check valve (not shown) which ting. The pump 2| is adapted to seat on the inlet fitting 12 automatically when it is moved downwardly through the supply tubing [1 into the pump receiver 20 so that it automatically assumes its operating position. The inlet fitting 12 is seated on an annular insert 13 which isdisposed in the bore 52 in the fitting 53 and which? is seated on a shoulder 74 therein.

Except for certain modifications required to adapt it to the closed tubing system of the invention, the free fluid-operated pump 2| maybe of conventional design and will not be described in detail. In general, the pump 2| includesa motor section and a pump section below the motor section, the motor and pump sections respectively including coupled motor and pump pistons (not shown). The motor section of the pump 2| is actuable by operating fluid under pressure delivered thereto by the supply tubing H, the operating fluid under pressure being adapted to enter the motor section of the pump through ports which serve as an intake 18 for the pump and which are in fluid communication with the supply tubing when the'pump i in its operating position. The ports of the intake 18 are formed in an intake fitting 19 which carries the aforementioned tapered head and which is connected to the upper end of a tubular rod 80 extending upwardly from th motor section of the pump 2|, the rod being adapted to convey the operating fluid under pressure from the intake to the motor section of the pump. After the operating fluid admitted to the motor section of the pump 2| through the intake 18 has actuated the pump, it is discharged from the motor section through ports forming an exhaust 8| for the pump. When the pump 2| is in its operating position, the exhaust 8| communicates with an annular space 82 between the pump and the liner 48 in the inner sleeve 39, this annular space communicatin with the return tubing. l8 through the ports 41 in the liner, the ports 46 in the inner sleeve 39, the annular space 44 between the inner -sleeve and the outer sleeve 43. and the ports 45 in the coupling 4|. Thus, the operating fluid under pressure in the supply tubing flows through the motor section of the pump 2| to actuate it and is discharged into the return tubing |8 as spent operating fiuid.

In order to prevent direct flow of operating fluid between the supply and return tubings l1 and I8 by way of the pump receiver 20, I provide .sealing means comprising annular sealing elements 86 and 81 which are carried by the pump 2| respectively above and below the exhaust 8| and which are adapted to engage the liner 48 respectively above and below the ports 41 in the liner when the pump 2| is in its operating posipump. Thus, the annular sealing elements 86 and 81 isolate the intake 18 and the exhaust 8| when the pump 2| is in its operating position so that the intake may communicate only with the supply tubing l1 and so that the exhaust may communicate only with the return tubing l8.

As previously mentioned, the pump section of the pump 2| is provided with an inlet at its lower end through which well fluid is adapted to enter the pump section by way of the inlet fitting 12, the inlet of the pump section not being shown specifically. The pump section of the pump is also provided with ports forming an outlet 88 for production fluid discharged by the pump section, the'outlet communicating with an annular space 89 which is disposed between the pump and the inner sleeve 5| and which communicates at its lower end with the ports 63 leading to the production tubing |9. Thus, production fiuid discharged by the pump 2| through the outlet 88 flows through the annular space 89, the ports 63and the annular space 64 into the annular space between the return and production tubings l8 and l9. It will be noted that the annular sealing element 81' is disposed between the exhaust 8| and the outlet 88 so that it preventsflow between the return and production tubings I8' and I9 when the pump is in its operating position. Also, since the pump 2| is seated on the inlet fitting 12 when in its operating position, the pump seat provided by the inlet fitting serves to prevent direct flow between the well and the tubings ll, l8 and I9. In order to prevent flow between the return and production tubings l8 and I9 by way of the passage means 66 when the pump 2| is in its operating position, the pump carries an annular sealing element 94 which is adapted to engage a liner 95 pressed into the bore 52 in the fitting 53 of the pump receiver 20. Considering the operation of the embodiment of the invention hereinbefore described, it will be assumed that the pump 2| is in operation to pump fluid from the well upwardly through the production tubing IE] to the surface. Under such conditions, the pump 2| is in its operating position in the pump receiver 20 so that it is seated on the inlet fitting 12, and operating fiuid under -'tubing' tion of the pump 2i through its inlet is dis- Y diners 48 and '95.

egusaoee 18 to actuate the pump, spent operating fluid being discharged into the return tubing through the exhaust BI and being conveyed upwardly in the well to the surface by the return The well fluid entering the pump seccharged into the production tubing l9 through the outlet-88 and is conveyed upwardly in the well'to the surface as production fluid. It will .be' apparent that, with this construotion,xthe

spent operatingfluid is returned to the surface separately from the production fluid so that it may be re-used to actuate the pump 2l,' which is a primary feature of the invention.

In the event that removal of the pump from the well is necessary in order to service or repair 'the pump, or for any other reason, it'is merely necessary to direct a flow of operating fluid .under pressure downwardly through the return tubing l8, instead of through the supply tubing 1 H.

This may be accomplished by connecting the return line 32 to the source of operating fluid under pressure, the supply line 3| preferably being connected to the reservoir associated withthe source under such conditions. As will be apparent, this may be accomplished by a suitable arrangement of. valves (not .3 shown). Also, fluid flow through the production tubing [9 'and the production line 33 under such conditions is preferably prevented, as by closing a valve 96 in the production line. Under the conditions outlined in the precedin paragraph, operating fluid under pressure flows a'downwardlythrough the return tubing 3 and into the annular chamber 68 at the lower end of the-pump 2| by way of the ports 45 in'the coupling ill, the annular space 44 between the inner sleeves 39 and 5| and the outer sleeve '43,

and the passage means 66'. The pressure of the operating fluid entering the annular chamber 68 in the foregoing manner .is applied to an annular area 91 at the lower end of the pump Zlso as to unseat the pump from the inlet fitting 12 and is then applied to the entire'area of the pump so as to move it upwardly in the pump receiver 20, upward fiow of the operating fluid applied to' 'the lower end of the pump in this manner pastl'the' pump being prevented by the annular sealing elements 86, 8'! and 94 which engage the After the pump 25 is moved upwardly in the pump receiver 26 a distance such that the annular sealing elements 85, 81 and 5t disengage the liners 48 and S5, upward flow of operating fluid past the pump is prevented by packing devices 93 and 99 which are carried by the rod 80 and which are adapted to engage the inner wall of the supply tubing IT in a substantially fluid-tight manner, the portions of the pump 2| which carry the annular sealing elements 86, 81 and 94 preferably being .of smaller diameter than the internal diameter of the supply tubing so as to prevent damage to the sealing be removed from the supply tubing through the since the valve 96 is closed during the pumpremoval operation, substantially none of the production fluid can enter the pump receiver 2t during the pump-removal operation, which isan important feature since it prevents sand, and other foreign matter which may be in the production fluid from entering the pump receiver. Thus, subsequent damage to the motor section of the pump from this source upon re-installation of the pump is prevented. It will also be noted that, under the conditions hereinbefore outlined, theoperating fluid in the supply tubing ll above the pump 2! may be returned to the reservoir associated with the source of operating fluid duringithe pump-removal operation so that substantiallynone of the operating fluid is lost from the system.

When re-installation of the pump 2|, or installation of a replacement pump 21, is desired,

it isinserted into the upper end of the supply tubing I! through the tube 34 at the upper end ofthe tubing head 29 and operating fluid under pressure is introduced into the supply tubing above the pump through the supply line 3!, the return line 32 preferably being connected to the reservoir associated with the source of operating fluid. Thus, the operating fluid under pressure entering the system through the supply line 3| acts on the upper end of the pump 2! to move it downwardly through the supply tubing l1 and into its operating position in the pump receiver 20 wherein it is seated on the inlet fitting 12,

to the reservoir.

the operating fluid previously introduced below the pump during the pump-removal operation beingv displaced upwardly through the return tubing 18 and into the return line 32 leading During the operation of installing the pump, the valve 96 in the production line 33 preferably prevents flow through the pro- I duction tubing [9 so that all of the fluid employed during the pump-removal operation is returned to the reservoir during rte-installation of the pump. It will be understood, however, that if the operating fluid in the supply tubing becomes contaminated prior to re-installation of the pump 2| for any reason, returning such contam- "inated' operating fluid to the reservoir may be iii)- pump avoided by preventing fluid flow through the return tubing l8 and by permitting fluid flow through the production tubing it.

As will be apparent, one advantage of the embodiment hereinbefore discussed is that it is possible to remove and re-install the pump 2| with "substantially no loss of operating fluid from the system, the production tubing l9 being isolated from that. portion of the system reserved for the operating fluid by the closed valve 96 during the operations of removing and re-installing the Another advantage of the embodiment hereinbefore disclosed is that it provides a production tubing 19 of large diameter so as to minimize friction losses between the production fluid :streamand the production tubing, which is an in portant feature, particularly in wells permit- "ting the use of a pump having a pump section of large capacity and a motor section of small capacity, since it provides a high ratio of production to power input.

Referring now to Figs. to 8 of the drawings, the embodiment of the invention illustrated therein is similar to that illustrated in Figs, 1 to 4 and the same reference numerals are employed to designate corresponding components insofar as applicable. The principal difference between the two embodiments is that, in the one illustrated in Figs. 5 to 8, the well casing i5 and'c'asing head 16 are eliminated, the production tubing l9 being the well casing. In order to isolate the column of production fluid from the well, I,, employ a packer I09 connected to the fitting 53 at the lower end of the pump receiver Zii. The passage 69' in the fitting 53 communicates with the well below the packer [Bil so that well fluid may enter the inlet of the pump 2| through the inlet fitting 12 ,as in the preceding embodiment.

ently under consideration is of somewhat different construction than the pump receiver of the previously considered embodiment, one of the differences being that the return tubing I8 is connected directly to the fitting 53, as, by being threaded thereon. The pump receiver includes the previously described inner sleeves 39 and-5|, a third inner sleeve llll being threaded into the upper end of the inner sleeve 39 and being threaded onto the lower end of the supply tubing l1. Instead of being threaded into the fitting 53, the lowermost inner sleeve 5| is tapered at its lower end and is seated on a complementary seat H32 in this fitting.

Except for the foregoing difierences, the embodiment of Figs. 5 to 8 is identical to that of operation of the embodiment of Figs. 1 to 4. Consequently, a detailed explanation of the operation of the embodiment presently under considoration is unnecessary. v

Although I have disclosed exemplary embodiments of the invention herein for purposes of illustration, it will be understood that I do not intend to be limited specifically thereto since vari'ous changes, modifications and substitutions may be incorporated in the illustrative embodiments disclosed without departing from the spirit of the invention.

I claim as my invention:

1. In a closed, fluid-operated, free-pump system for a well, the combination of: concentric supply, return and production tubings set in the well and respectively adapted to convey operating fluid downwardly into the well from the surface, spent operating fluid upwardly in the well to the surface and fiuid produced by the well upwardly therein to the surface; means for interconnecting the lower ends of said tubings in fluid communiproduced by the well upwardly therein to the sur- "seated on said pump seat, said pump having an "intake, an exhaust and an outlet which communicate with said tubings, respectively, when .said pump is in said operating position, and having an inlet which communicates with the well when said pump is in said operating position.

3. In a closed, fluid-operated, free-pump system for a well, the combination of: concentric supply, return and production tubings set in the well and respectively adapted to convey operating fluid downwardly into the well from the sur- Figs. 1 to 4, and its operation is identical to the cation with each other and with the well; and

a fluid-operated, free pump movable in the innermost, of said tubings into an operatingposition at the lower end thereof, said pump having an intake, an exhaust, an inlet and an outlet which communicate with saidsupply tubing, said return tubing, the well and said production tubing, respectively, when said pump is in said operating position.

2. In a closed, fluid-operated, free-pump system' for a well, the combination of: three concentric tubingsset in the well and respectively adapted to convey operating fluid downwardly 'into the well from the surface, spent operating fluid upwardly in the well to the surface and fluid face, spent operating fluid upwardly in the well to the surface and fluid produced by the well upwardly therein to the surface; a tubular pump receiver at the lower end of and aligned with the innermost of said tubings, said pump receiver being connected to the lowerends of said tubings in fluid communication therewith and being in" fluid communication with the well; and a fluid-operated, free pump movable in said innermost tubing and movable into an operating position in said pump receiver, said pump having an intake, an exhaust, an inlet-and an outlet which communicate with said supply tubing, said returntubing, the well and said production tubing, respectively, when said pump is in said operating position.

4. A closed system as set forth in claim 3 in cluding sealing devices for normall preventing direct flow of fluid between said tubings and the well when said pump is in said operating position.

5. In a closed, fluid-operated, free-pump system for a well, the combination of: concentric supply, return and production tubings set in the well and respectively adapted to convey operating fluid downwardly into the'well from the surface, spent operating fluid'upwardly in the well .to the surface and fluid produced by the well upwardly therein to the surface; a tubular pump receiver connected to the lower ends of said tubings in alignment with the innermost of said-tubings, said pump receiver communicating at its upper end with said innermost tubing and having substantially the same internal diameter as said innermost tubing, and said pump receiver having passages which provide fluid communication between the others of said tubings and saidpump receiver and between the well and said pump receiver;a pump seat carried by said pump rmeiver at the lower end thereof and in alignmenttherewith; a fluid-operated, free pump movable in said innermost tubing and movable into an operating position in said pump receiver wherein it is'seated on said pump seat, said pump having an intake, an exhaust, an inlet and an outlet which "receiver and between-the well and said pump receiver; a pump seat carried by said pump receiver at the lower end thereof' and in alignment there'- with; a fluid-operated, free pump movable in -said innermost tubing and movable into an'operating position in said pump receiver wherein it is seated on said pump seat, said pump having an intake, an exhaust, an inlet and an outlet which communicate with said supply tubing, said return tubing, the well and said production tubing, irespectively, when said pump is in said operating position; .sealing devices for normally preventing direct flow'of fluid between said 'tubings and the well-by way of said pumpreceiver when-{said pump is in said operating position; a chamberin said pump receiver between saidpump seat and said pump; and passage means providing fluid communication between saidchamber and one of said tubings other than said innermost tubing.

7. In a closed,fiuid-operat ed, free-pumpsysitem for a well, the combination of concentric supply, return and production tubing-s set in'the well and respectively adapted to convey operating fluid downwardly into'the well from the surface, spent operating fluid upwardly in the well to the surface and fluid produced by the well upwardly therein to the surface; a tubular pump receiver connected to the lower ends of said tubings in alignment with the innermost of said tubings, said pump receiver communicating at its upper end with said innermost tubing and having substantially the same internal diameter as said innermost tubing, and said pump receiver having passages which provide fluid communication between the others of said tubings and said pump receiver and between the well and said pump receiver; a pump seat carried by said pump receiver at the lower end thereof and in alignment therewith; a fluid-operated, free pump movable in said innermost tubing and movable into an operating position in said pump receiver wherein it is seated on said pump seat, said pump having an intake, an exhaust, an inlet and an outlet which communicate with said supply tubing, said return tubing, the well and said production tubing, respectively, when said pump is in said operating position; sealing devices for normally preventing direct flow of fluid between said tubings and the well by way of said pump receiver when. said pump is in said operating position; a chamber in said receiver between said pump seat and said pump; passage means providing fluid communication between said chamber and one or" said tubings other than said innermost tubing; and another sealing device for normally preventing flow of fluid between said passage means and said production tubing.

8. A closed system as set forth in claim '7 wherein said other sealing device comprises an annular "sealing element positionable between said pump and said pump receiver.

9. A closed system as set forth in claim 1 wherein said innermost tubing is said supply tubing.

14 10; A closed system" as set" forth in claimwl wherein said innermost tubing is. said supply tubing and wherein the intermediate and-outermost tubings are said return and production tubings, respectively.

' 11. A closed system as set forth in-claim -1 wherein the outermost of said tubings is the casing of the well.

12. In a closed, fluid-operated, free-pump systern for a well, the combination of: concentric supply, return and production tubings set in the well and'respectively adapted to convey operating fluid downwardly into the well from the surface, spent operating fluid upwardly in the well to the surface and fluid produced by the-well upward-1y therein to the surface; means for interconn'e'cting the lower ends of said tubings in fluid communicationwith each other and with the well; a fluid-operated, free pump movable in the innermost/of said tubings into an operating position at the lower end thereof, said pump having'an intake, an exhaust, an inlet and an outlet which communicate with said supply tubing, said return tubing, the well" and said production tubing, respectively, when said pump is in said operatin-gpo'sition,- means for preventing direct flow'of fluid between said'tubings and the well by way of said interconnecting means when said pump is in said operating position; and passage means communicating with said innermost tubing and with one of the others of said tubings'for applying a downward flow of" fluid through'said one other tubing to the lower end of said pump to move said-pump upwardly from its op'erating position through said innermost tubing to the surface.

13; A closed system as set forth in claim 12 wherein said innermost tubing is said supply tubing.

14'. A closed system as set forth in claim 12 wherein said innermost tubing is said supply tubing, and wherein the intermediate and outermost tubings are said return and production tu-bings. respectively.

15. A closed system as set forth in claim 12 wherein said one pther tubing with which said passage means communicates is said return tubing.

16. A closed system according to claim 12 wherein said production tubing is of larger diameter than at least one or" the other two tubings.

17. A closed system as defined in claim 12 wherein said production tubing is of larger diameter than either of the other two tubings.

18. In a closed. fluid-operated, free-pump system for a well, the combination of: concentric supply, return and production tubings set in the well and respectively adapted to convey operating fluid downwardly into the well from the surface, spent operating fluid upwardly in the well to the surface and fluid produced by the well upwardly therein to the surface, said supply tubing being the innermost of said tubings; a tubular pump receiver at the lower end.of and aligned with said innermost tubing, said pump receiver being connected to the lower ends of said tubings in fluid communication therewith and being in fluid communication with the well; a fluid-operated, free pump movable in said innermost tubing into an operating position in said pump receiver, said pump having an intake, an exhaust below said intake, an outlet below said exhaust, and an inlet below said outlet, said intake, said exhaust, said inlet and said outlet respectively communicating with said supply tubing,

15 i said return tubing, the well-and said production tubing when said pump is in said operating position; an annular sealing element carried by said pump intermediate said intake and said exhaust and engageable with said pump receiver when said pump is in said operating position; another annular sealing element carried by said pump intermediate said exhaust and said outlet and engageable with said pump receiver when said pump is in said operating position; and sealing means providing a fluid-tight seal between said inlet and said outlet when said pump is in said operating position. 1

19. A closed system according to claim 18 including a passage communicating at one end with said return tubing and at; its other end with said pump receiver at a point which is intermediate said other annular sealing element and said sealing means when said pump is in its operating position, said system including asealing device for normally preventing flow'from said return to said production tubing by way of said passage when said pump is in said operating position.

20. A closed system as. setyforth in claim 19 wherein said sealing device comprises an annular sealing element carried by said pump below said outlet. and engageable with said pump receiver .when said pump is in said operating position.

21. In a closed, fluid-operated, free-pump system, the combination of: a primary tubing and a pair of secondary tubings se't lin the well concentrically with said primary-tubing innermost,

said primary tubing being of a size to receive a fluid-operated, free pump and providing ,for

movement of the pump between an operating position at the lower end of said primary tubing and the surface; means interconnecting the lower ends of said tubings, said interconnecting means having passage means providing fluid communication between one of said secondary tubings and said primary tubing and having passage means providing fluid communication between the other of said secondary tubings and said primary tubing; inlet means connected to said primary tubing and'having a passage providing fluid communication between the well and said primary tubingfsaid inlet means having means for preventing flow of fluid from said primary tubing into the well through said passage; and sealing means providing a fluid-tight seal between said secondary tubings. 4

' CLARENCE J. COBERLY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

